Ambrose wrote the hymn "O Trinity, O Blessed Light"

A lawyer and civil servant in the Roman empire, Ambrose was acclaimed by the lay folk of the diocese of Milan as their bishop in 374. As bishop, Ambrose was noted for combating both paganism and the Arian heresy, for his knowledge of Greek theology, for his strong insistence on the independence of the church over against the civil authorities. His hymns include "Savior of the Nations, Come," "O Trinity, O Blessed Light," and others still sung. Ambrose is also remembered as the mentor of the young convert, Augustine of Hippo.